#983 – Using a BitArray to Store a Large Collection of Boolean Values

If you need to store a set of boolean values, you can store them in array of type bool.  Each element of the array would require 8 bits, despite storing a single boolean value.

You can more efficiently store a set of boolean values in an enum type, marking the type with the Flags attribute.  This allows storing a maximum of 32 distinct boolean values.

To store a larger collection of boolean values, you can use the BitArray type.  A BitArray allows you to index into an array of boolean values, but stores the values in a more compact form than would be used by a normal array.

Below, we use an enum to index into a 50-element BitArray.

        public enum States
        {
            Alabama,
            // ...
            Wyoming
        }

            BitArray baStatesIveVisited = new BitArray(50);

            baStatesIveVisited[(int)States.Minnesota] = true;
            baStatesIveVisited[(int)States.Wisconsin] = true;
            baStatesIveVisited[(int)States.California] = true;

            States nextState = States.Alabama;
            foreach (bool b in baStatesIveVisited)
                Console.WriteLine("{0}:{1}", nextState++, b);

983-001

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #983 – Using a BitArray to Store a Large Collection of Boolean Values

  1. Pingback: Dew Drop – November 27, 2013 (#1673) | Morning Dew

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